Crossfill is the wrong term. Crossfill is a feature on the 430W when it connects directly to another 430W or 530W to exchange waypoint data and Flight plans. This works by connecting RS-232 #4 if I remember correctly and both 430W must be on the same Flight Database Version or it will not work.
If you want to have your 696 learn the flight plan or Direct to from your 430w, that is possible by simply connecting a free RS232 Output on the 430W to the input of your 696. The 430W and 696 will need to be setup for Aviation Format. So the 430W will be doing Aviation Out and the 696 will do Aviation In. There is now way to have the 430W learn the flight plan from the 696, only one way from 430W to 696 as I described.
Thanks
Ray